The antibiotic pipeline for gram-negative bugs is dry. Newly evolved strains of some bacteria can be resistant to nearly every antibiotic, so they are bringing back old, old antibiotics. The issue is that old antibiotics are not as good at differentiating human cells and bacterial cells, they just kill all cells, so have horrible side effects. Consider that antibiotics have been in use for only decades. Humans have invented many great antibiotics that were super effective (!), and in a mere 40 or so years, many bacteria have already evolved to be resistant to all of them? They are really amazing organisms and will keep evolving as fast as we create new antibiotics, which is not very fast any more. How do you think we will deal with this issue in another 2 decades when VRE, MRSA and other super-bugs are more prevalent?